Mesa (master): meta/decompress: Don't pollute the sampler object namespace

[Ian Romanick]

Module: Mesa
Branch: master
Commit: ae50157363e828a50b249743d3f0b83322a3bc3a
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=ae50157363e828a50b249743d3f0b83322a3bc3a

Author: Ian Romanick <ian.d.romanick at intel.com>
Date:   Tue Nov 10 16:33:02 2015 -0800

meta/decompress: Don't pollute the sampler object namespace

tl;dr: For many types of GL object, we can *NEVER* use the Gen function.

In OpenGL ES (all versions!) and OpenGL compatibility profile,
applications don't have to call Gen functions.  The GL spec is very
clear about how you can mix-and-match generated names and non-generated
names: you can use any name you want for a particular object type until
you call the Gen function for that object type.

Here's the problem scenario:

 - Application calls a meta function that generates a name.  The first
   Gen will probably return 1.

 - Application decides to use the same name for an object of the same
   type without calling Gen.  Many demo programs use names 1, 2, 3,
   etc. without calling Gen.

 - Application calls the meta function again, and the meta function
   replaces the data.  The application's data is lost, and the app
   fails.  Have fun debugging that.

Signed-off-by: Ian Romanick <ian.d.romanick at intel.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=92363
Reviewed-by: Jason Ekstrand <jason.ekstrand at intel.com>

---

 src/mesa/drivers/common/meta.c |   22 +++++++++++++++-------
 1 file changed, 15 insertions(+), 7 deletions(-)

diff --git a/src/mesa/drivers/common/meta.c b/src/mesa/drivers/common/meta.c
index 385ea64..8f93b25 100644
--- a/src/mesa/drivers/common/meta.c
+++ b/src/mesa/drivers/common/meta.c
@@ -2986,8 +2986,7 @@ meta_decompress_cleanup(struct gl_context *ctx,
       _mesa_reference_buffer_object(ctx, &decompress->buf_obj, NULL);
    }
 
-   if (decompress->samp_obj != NULL)
-      _mesa_DeleteSamplers(1, &decompress->samp_obj->Name);
+   _mesa_reference_sampler_object(ctx, &decompress->samp_obj, NULL);
 
    memset(decompress, 0, sizeof(*decompress));
 }
@@ -3114,12 +3113,21 @@ decompress_texture_image(struct gl_context *ctx,
    }
 
    if (decompress->samp_obj == NULL) {
-      GLuint sampler;
-
-      _mesa_GenSamplers(1, &sampler);
+      decompress->samp_obj =  ctx->Driver.NewSamplerObject(ctx, 0xDEADBEEF);
+      if (decompress->samp_obj == NULL) {
+         _mesa_meta_end(ctx);
 
-      decompress->samp_obj = _mesa_lookup_samplerobj(ctx, sampler);
-      assert(decompress->samp_obj != NULL && decompress->samp_obj->Name == sampler);
+         /* This is a bit lazy.  Flag out of memory, and then don't bother to
+          * clean up.  Once out of memory is flagged, the only realistic next
+          * move is to destroy the context.  That will trigger all the right
+          * clean up.
+          *
+          * Returning true prevents other GetTexImage methods from attempting
+          * anything since they will likely fail too.
+          */
+         _mesa_error(ctx, GL_OUT_OF_MEMORY, "glGetTexImage");
+         return true;
+      }
 
       _mesa_bind_sampler(ctx, ctx->Texture.CurrentUnit, decompress->samp_obj);
       /* nearest filtering */